Embodiments of the invention relate to solid state power controllers (SSPCs), and in particular to controlling gates of an SSPC to provide soft turn-on and turn-off characteristics.
Solid state circuit breakers (SSCBs) are used in power distribution systems to replace traditional electromechanical circuit breakers. SSCBs distribute power and provide over-current or over-voltage protection to different loads. Compared with electromagnetic devices, SSCBs provide a fast response time and eliminate arcing during turn-off transient and bouncing during turn-on transient. SSCBs do not suffer severe degradation during repeated fault isolation in comparison with electromechanical devices. In addition, SSCBs have a smaller weight and size than traditional electromechanical circuit breakers.
The silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) is used in SSCB applications due to its low conduction loss. However, during turn-off, the SiC MOSFET may cause significant electromagnetic interference (EMI) due to its high frequency ringing. The ringing is caused by the output capacitance of the SiC MOSFET resonating with the stray inductance in the high current path. There is a need to improve SSCB control to minimize EMI noise during switching and reduce overvoltage stress on SiC MOSFET during turn-off event, especially at short circuit conditions.
In addition, SSCBs used as a part of a solid state power controller (SSPC) may need to support nontraditional functions such as in-rush current limiting during channel closure into capacitive load and current limiting in the event of short circuit faulty loads.